1. Field of the Invention
The present invention relates generally to the field of integrated circuits and more specifically to an integrated circuit comprising a microprocessor and at least one internal peripheral circuit whose operating speed has been improved. A circuit of this type is called a microcontroller.
Microcontrollers are systems generally consisting of a microprocessor or central processing unit and a plurality of internal peripheral circuits required for the operation of the system. These internal peripheral circuits are for example a read-only memory that contains the program to be used by the microcontroller, a programmable memory or a coprocessor.
2. Description of the Prior Art
In the prior art, the speed of operation of the microcontrollers is fixed at the time of their manufacture as a function of the internal peripheral circuits that they contain. This speed is dictated by the internal clock signal of the microcontroller. This signal is fixed and its period is chosen so that all the internal peripheral circuits of the microprocessor can work properly. For example, if the microcontroller has a ROM type memory and an EEPROM type memory respectively having access times t1 and t2, the period of the internal clock signal is taken to be greater than or equal to the greatest of the two access times (in practice t2) so that the slowest of these two memories has the necessary time available to carry out the operation controlled by the microprocessor. The duration of an internal clock cycle is therefore permanently greater than or equal to the duration of the read or programming cycle of the slowest memory. More generally, this makes it possible to ensure that, whatever may be the internal peripheral circuit activated by the microprocessor, this circuit will have the time needed to process the instruction coming from the microprocessor.
The speed of operation of the microcontroller is therefore dictated by the slowest internal peripheral circuit of the microcontroller. The overall operation of the microcontroller is thereby then penalized.
In the invention, it is planned to overcome this drawback by matching the operating speed of the microcontroller to the operating time of the internal peripheral circuit activated by the microprocessor.